Aromatic polyamide films are being investigated for a variety of uses which will allow benefit from advantages such as their heat-resistance and mechanical properties. In particular, para-oriented aromatic polyamides are superior to other polymers with respect to mechanical properties such as stiffness and strength and the like, so that they offer great advantage in making films thinner and they are also being investigated for use in printer ribbons, magnetic tapes, condensers and the like. With regard to magnetic recording media, these are disclosed in Japanese Unexamined Patent Publication No. 58-168655 and Japanese Unexamined Patent Publication No. 62-112218 and the like.
In the field of magnetic recording media, a metallic-thin-film-type magnetic recording medium seems to be showing promise in increasing recording density, wherein Co, Ni, Cr, or the like, is deposited on a substrate film by vacuum evaporation deposition, cathode sputtering, ion plating or the like to form the metallic-thin-film-type magnetic recording medium. The metallic-thin-film-type magnetic recording medium cannot only increase recording density in the film but can also make a magnetic layer thinner, so that the entire thickness of the recording medium becomes thin and the film can be made longer. The metallic-thin-film-type magnetic recording medium, therefore, is very useful in increasing storage capacity.
A heat-resistant film is useful for reducing damage caused by heat, because the magnetic recording medium is heated at the deposition of the magnetic layer. However, the film curls greatly, so that it is difficult to uncurl. To address this problem, for example, there is disclosed in Japanese Unexamined Patent Publication No. 56-16938 a range of heat-shrinkage rates which are necessary for uncurling the film at high temperature. It has, however, been clear that the above-disclosed range is not satisfactory in reproducibly providing a smooth magnetic tape.
An object of the present invention is to address the problem described above and to provide an aromatic polyamide film for reproducibly producing a smooth magnetic recording medium and a magnetic recording medium using the film while utilizing its high degree of stiffness and its heat-resistance.